1. Field of the Invention
The present invention relates to a light amount adjuster, a lens barrel, and an image pickup device.
2. Description of the Related Art
There is used a light amount adjuster (diaphragm device) built into a lens barrel of an image pickup device such as a video camera and a digital still camera.
As light amount adjusters, there are two kinds of devices being in use. One is a device adopting an iris diaphragm which adjusts a size of a diaphragm aperture by swinging a plurality of diaphragm blades arranged around the diaphragm aperture in an interlocking matter. The other is a device in which two diaphragm blades are slid along a line orthogonal to an optical axis, sandwiching the diaphragm aperture (see JP-A No. 2000-352736).
The former light amount adjuster has a structure in which two or more diaphragm blades are arranged around the diaphragm aperture. Therefore, since there is a growing demand for a large space in a periphery of the diaphragm aperture, it is disadvantageous in making a device compact.
On the other hand, the latter light amount adjuster has a structure in which two diaphragm blades are slid along a straight line. Since there is not a growing demand for a large space on both sides of the diaphragm blades, it is advantageous in making the device compact.